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Topic: Plastic vs steel breather gear (Read 5905 times)

Just wanted some feedback on which was better Plastic or Steel breather gears on a mild build. Seems the plastic would protect the case where as the steel would gouge the bore in the event of a piece of debrie getting wedged.

I seem to recall that the original idea behind the steel breather was that crap wouldn't get imbedded in it. I guess with the plastic it get's imbedded in it and just keeps going around and around. If you don't already have either, what about the reed valve?

Have read here that the plastic can and will get metal pieces imbedded and the steel has a finer mesh to keep the junk out. Wonder where the junk goes if it is travelling through and not able to go anywhere? Also, the metal is supposed to let it breath better. The metal ones are not cheap eather!

Metal is better. Metal gets embedded in the plastic one like Gryphon said & scores up the bore. I'm rebuilding a 63 Panhead now & the breather bore looks like the day it was bored. HD used steel back then.

That's kind of a trick question. The standard breather is timed. The reed works on pressure. The reed makes for a nice replacement when the bore got buggered by the plastic. I've used both with good results. The screen in the steel one can be restrictive on bigger motors. For a stock or slightly modified motor either one works fine. On bigger motors you may find that one works better than the other.

I put an S&S reed valve in my 80 in evo.....EV27 cam, dyna single fire ignition, S&S carb....when I did the top end last winter. The intention was to reduce the oil misting from the crank case ventilation....can't say that there was any improvement in that regard. The misting was actually worse until the rebuild got broken in (to be expected) but it is about the same now as it always was with the old plastic breather in there.

Just letting you know my experience.....I haven't bothered to go in and take it out...it's not that it doesn't work...it's just on my evo with my set up it doesn't seem to work any better.

Reddog, I recently bought a Ultima steel breather and I thought the quality was very good. Hardened with a nice ground finish. Jireh has it for only $35.00. Its the same gear they use in their 140 CI so i guess it flows good. Only 200 miles on it so far and all is good.

A while back (on the old MSN site I believe) someone posted a photo of an S&S reed breather where the reed have broken off. Might be an option for a motor with a buggered breather bore. But for normal use, I'd go with the steel breather gear.

I pulled the plastic breather out of my '88 evo. The breather and the bore are all tore up. Can't do anything about the bore, but put a steel one in. Now if I can just rebuild the rest of the engine!

The steel gear is available in .030" over, if you've got the engine torn down. I've bored many a case for one, or you could go with the S&S reed.

The plastic gear was another attempt by the factory to save money, and they won't damage you're cases unless there's some debris to help, but if there ever is, it'll tear the case up worse than a steel gear would.

Just wanted some feedback on which was better Plastic or Steel breather gears on a mild build. Seems the plastic would protect the case where as the steel would gouge the bore in the event of a piece of debrie getting wedged.

I see no advantage in one over the other in a Evo motor. If the engine is throwing garbage out the breather, the cases get tore up. Now with the plastic breather you can drill holes in it to get it timed, or you could grind the cases as Hillside stated. You can also elongate the one hole in the plastic so it will pull more oil out of the breather cavity in 93 and earlier Evos. In a Shovel, that has the primary hoses connected to the engine, steel is the way to go. The reed breather I have never installed one.

When I walked into the shop with my cam and stuff in a box, the first words out of his mouth was "get rid of that", I said What? He said that nylon breather, the nylon goes out of round when hot, and the nylon itself will tear up the case. I trust that shop and what they say. $.02

S&S Reed in mine, no muss, no fuss and it did reduce the misting alot.

My experience as well. Recently got my big bore '87 FXLR back up and went with the reed valve. I had a breather misting (puking) issue before and that's all gone now. Don't know exactly how much to contribute to the reed valve though as it naturally got a new top end w/the BBK and I'm running head breather heads as well as the crank breather. It's really nice to be able to park it now without it "marking it's spot".

Can you give me some more info on that valve. I googled it but can't find anything...all I have on my crank vent now is a filter....if there is some kind of PCV valve I can use to improve the misting I would like to try it.